Over time, the usefulness and benefits of stand alone computing devices, such as the ubiquitous personal computer, have been leveraged by allowing many of such computing devices to communicate with one another over a communications network. Network communication between computers allows many different kinds of applications to exist that are otherwise not possible with a stand-alone computer.
For communicating over a network, information that is to be transported from one computer to another is divided into a number of network communication packets. These network packets (also known simply as “packets”) will eventually be transported across the physical communications network. In the PC environment, transmission is handled by a network interface card residing in the personal computer. Throughout this application the PC environment will be assumed, though the discussion and application of the concepts apply to many different network computing environments as will be appreciated by those skilled in the art.
Delays due to network traffic had little impact on the quality of service for the first types of network applications; namely file transfer and messaging applications. Currently, multimedia applications have streaming data, such as successive sound or video, that is communicated from one computer to another. Streaming data typically refers to a continuous set of successive packets that, in order to be processed correctly at the receiving computer, must have certain guaranteed transmission characteristics. Streaming data must be processed at a certain rate, and that rate must be maintained over the network connection. Additionally, there is a limitation on the amount of variability between when successive packets are received. Should the rate and variability requirements not be met, packets will not be received and processed appropriately by the receiving computer and perceptible errors will occur. For example, a video frame may be lost or temporarily frozen if there is some sort of interruption in the stream of packets being processed.
In order to assure a certain quality of service, reservation of network bandwidth or other relevant resource is required. A number of different protocols have been developed, such as RSVP and ATM, for making bandwidth reservations on all nodes that would be in charge of carrying network communication packets between the source and destination nodes. In this manner, once the bandwidth reservations are made, the packets may be sent as part of a data stream, or packet flow, from the source node to the destination node with the assurance of a certain quality of service due to bandwidth reservations.
While these protocols generally work for their intended purpose, there are a number of disadvantages associated with their use. For example, owing to the lack of uniformity across the protocols, there exists no relatively simple manner by which traffic control parameters can be verified, queried, or set. Additionally, it is not desirable to have many different application programs attempting to communicate with one another so as to determine the necessary classifications and schedules to maintain quality of service for the various packets to be sent.